Build and run the samples in CI, and fix the one that was already broken

[Rafael-SOWNet]

Closes the gap that #846 exposed: nothing in CI built anything under Sources/Samples.

Why building them is not optional

That gap is why SampleNet5 and FSharpSample stayed broken against the current release for seven months while looking healthy. They were pinned to AngouriMath 1.3.0, so they compiled against a version that still accepted integral(f, x, 1). Unpinning them in #846 was only half the fix — a sample that nothing builds will break again.

Why running them is not optional either

Both of those samples compiled cleanly and threw at runtime. A build-only job would have passed on both. The console samples are therefore run as well; each takes about two seconds.

Writing this found a third one

FSharpPlayground already used a ProjectReference, so nothing was concealing it — it is broken on master today:

FunctionArgumentCountException: integral should have exactly 4 arguments
or 2 arguments but 3 arguments are provided
   at <StartupCode$FSharpPlayground>.$Program.main@() in .../FSharpPlayground/Program.fs:line 15

Same call, integral(y + 3, y, 1). Nothing was hiding this one at all; it simply was never run. Fixed here to the two-argument form, and it now completes.

That is the argument for the job in one example: the pin explained two of the three, and the third was broken in plain sight.

What runs and what only builds

sample	built	run	why
SampleNet5	✅	✅
FSharpSample	✅	✅
FSharpPlayground	✅	✅
Playground	✅	✅
InteractivePlayground	✅	❌	Plotly opens a browser
AngouriMathPlot	✅	❌	windowed application
GraphicExample	✅	❌	windowed application

The steps go in EverythingBuild.yml, which already runs on windows-latest — so the two windowed samples compile there, which they cannot do on Linux (NETSDK1100).

Measured locally

All four console samples build and exit 0:

SampleNet5        exit=0   2s   34 lines
FSharpSample      exit=0   1s   18 lines
FSharpPlayground  exit=0   2s   36 lines   (after the fix; exit=134 before)
Playground        exit=0   1s    7 lines

YAML parses and the job resolves to nine steps.

🤖 Generated with Claude Code